Pump assemblies for use in a motor vehicle for the purposes of assistively or exclusively supplying negative pressure to a pneumatic brake booster are basically known.
For example, dual-diaphragm pump assemblies are known which have an electric-motor drive, a crank mechanism which comprises two eccentric elements, and two elastic displacement elements which can be driven by the crank mechanism. To ensure an intended sequence of movements of the displacement elements over time, the crank mechanism has relative-rotation prevention means which prevent a rotation of eccentric elements relative to one another and ensure a defined rotational angle position of the eccentric elements relative to one another. It is known for such relative-rotation prevention means to be realized by way of two clamping pins which engage simultaneously into corresponding bores of two adjacent eccentric elements and thereby prevent the rotation of said eccentric elements relative to one another.
To ensure operation of the pump assembly with a low level of vibration, it is furthermore known for the eccentric elements to be equipped with balancing elements which serve as compensating weights on the crank mechanism and which reduce vibrations during operation. For example, it is known for the eccentric elements to be produced integrally with the balancing elements in a sintering process.
Likewise known are pump assemblies of the generic type mentioned in the introduction which have air ducts integrated in the pump housing, said air ducts having an interface in the plane of the displacement element. It is known for said interfaces to be sealed off by way of separate sealing elements such as O-rings. The expenditure in terms of the production and assembly of the pump assemblies mentioned in the introduction is considered to have potential for improvement.